This American Viticultural Area (AVA) is located entirely within the coastal zone of Mendocino County, California. The viticultural area was established on October 27, 1997. The boundaries of the 262,400 acres (410 sq mi) AVA encompass the coastal ridges at or above 1,200 ft (366 m) in elevation adjacent to the Pacific Ocean that reach inland toward the Anderson Valley. Roughly 36 mi (58 km) of the southernmost portion of the Mendocino coastline forms the AVA western border, with the Sonoma County line as the southern boundary, the Navarro River is the northern boundary and Anderson Valley outlines the inland boundary running northwest–southeast. Mendocino Ridge is essentially a northern extension of the Sonoma Coast viticultural area. Mendocino Ridge AVA designation is unique by its elevation where vineyards lie at or above 1,200 ft (366 m). This means Mendocino Ridge is the only non-contiguous AVA in the United States. The Mendocino Ridge AVA has been nicknamed “Islands in the Sky,” because the thick fog moving inland from the Pacific Ocean blankets the coast and the valleys between the ridge tops, making the tops of the mountains, where the vinyards lay, look like islands protruding from a sea of fog. Mendocino Ridge AVA lies above the Anderson Valley and Mendocino appellations. The Mendocino Ridge viticultural area contains approximately 1,500 to 2,000 acres (607–809 ha), about 2% of the total acreage, that are suitable for vineyards. The local hillsides are very steep (often above 70%) and covered with timber, making them unfit for viticulture. Estimates of planted acres range from 233 to 410, which accounts for about 0.3% of the total area.

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